機(jī)械硬盤---討論

easylife

原帖由 紫木棉 于 2009-2-3 23:58 發(fā)表

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8 \9 L* j$ w4 Q6 a$ ~* I2 k2.5"的機(jī)械盤最厚的地方有15mm，這是希捷250G的硬盤厚度,，我測(cè)量過(guò)，廠家的資料也是這個(gè)數(shù)據(jù),。
今天看到了一個(gè)目前我知道的最薄的2.5"固態(tài)硬盤,，Intel的產(chǎn)品，主要用在筆記本方面,。大概只有6-7mm厚,，外殼應(yīng)該是 ...

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1 C0 ?4 e, q, ?$ {在單位存儲(chǔ)容量?jī)r(jià)格上，機(jī)械硬盤是存在絕對(duì)的優(yōu)勢(shì)的,，08年9月底買了希捷的250gG單碟3.5盤,，才334元，1.34元/GB,。

easylife

原帖由 紫木棉 于 2009-2-4 00:05 發(fā)表

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# T: X( `! Y) M2 K2 i! q2 x3 l“熱輔助讀寫技術(shù)”——能否介紹一下這個(gè)技術(shù),？

自己不會(huì)描敘，借用他人的介紹:

Heat Assisted Magnetic Recording (HAMR):
( k0 C: _4 w, XHAMR shows the promises to be the key enabling technology that will increase the areal density to a level breaking through the so-called super paramagnetic limit of magnetic recording. This technology is expected to deliver storage densities as high as 50 terabits per square inch. If disk drives are produced to have such a great areal density, one can store the entire printed contents of the Library of Congress on a single disk drive. If the phenomenal growth rate of bit density continues, the size of an individual bit will soon reach such a small dimension that the bits become magnetically unstable. At that stage, though the bits can be written very tiny, they may not be suitable for information storage as some of them may flip into different polarization. This phenomenon is known as super paramagnetism. This problem can be overcome by heating the medium with a laser beam at the precise spot where a data bit is being recorded and subsequently cooling the spot rapidly to stabilize the written bit. Heating makes it easier to write on the medium. This heat assisted recording can increase the recorded density dramatically.

easylife

還有另一種技術(shù):

4 k4 d! N# ?. p8 e& I4 gPatterned Media:
5 O5 [, n: Z6 A; K( }Another promising approach to circumvent the density limitations imposed by the super paramagnetic effect is the use of patterned media. Conventionally, the disk is coated with a thin layer of magnetic alloy. If the disk surface is examined at high magnification, it becomes apparent that within each bit cell there are many tiny magnetic grains. These grains are randomly created during the deposition of the magnetic film. Each grain behaves like an independent magnet whose magnetization can be flipped by the write head during the data writing process. In patterned media, the magnetic alloy is not coated on the entire disk surface. The layer is created as an ordered array of highly uniform tiny islands, each island capable of storing an individual bit. Each bit is stored in a single deliberately formed magnetic switching volume. This may be one grain, or several exchange coupled grains, rather than a collection of random decoupled grains. Single switching volume magnetic islands are formed along circular tracks with regular spacing. Magnetic transitions no longer meander between random grains, but form perfectly distinct oundaries between precisely located islands. Since each island is a single magnetic domain, patterned media is thermally stable, even at densities far higher than can be achieved with conventional media. Though the concept of patterned media looks simple, realization of this to achieve high recording density is immensely challenging. For an areal density of 100 Gbits/square inch, the center to center spacing between two islands need to be 86 nanometers. For 10 terrabits/square inch density, this spacing is only 9 nm. Creating islands of such dimension is beyond
5 a% {3 Y) l# t: m( ^+ k4 Fthe capabilities of optical lithography. E-beam lithography and nano imprint replication are considered to be two approaches that can be used to realize patterned media commercially.
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The HDD industry will soon embrace these and other technologies to manufacture commercially hard disk drives with extremely high areal density. This makes the design of the head positioning servomechanism more challenging. Shrinking bit size also means narrower track pitch. Many disturbances ignored today will ask for special attention at such high track density. Ultra high areal density will also require the head to fly very low such that occasional contact between head and disk will become inevitable. The servomechanism must be robust enough to withstand these unpredictable disturbances.

紫木棉

我在網(wǎng)上查閱了一下,，應(yīng)該就是你上面介紹的兩種方法吧,，不過(guò)只是粗略的介紹了一下。

(1) 高溫讀寫,，常溫保持
% K" c! w5 g2 H, }. V- ~) e% _! U　　從磁性材料的特性方面著手,，尋找更為穩(wěn)定的磁介質(zhì)（如鐵鉑粒子），可以在一定程度上解決超順磁效應(yīng)的問(wèn)題,。不過(guò),，隨之而來(lái)的問(wèn)題是：現(xiàn)有的磁頭無(wú)法將數(shù)據(jù)寫到這類介質(zhì)上，于是希捷公司正在研究一種熱輔助磁記錄技術(shù) (Heat Assisted Magnetic Recording,，HAMR),，使用激光熱輔助手段將數(shù)據(jù)記錄到高穩(wěn)定性介質(zhì)上，而且隨后的快速冷卻又可以使已寫入的數(shù)據(jù)變得穩(wěn)定,。
3 k& s" D3 k6 R  Y, q) `　　不管怎樣,，目前激光技術(shù)完全可以為這一思路提供支援，是一條可行的技術(shù)路線,。Hitachi-IBM也十分看好這條路線,，他們給這項(xiàng)技術(shù)的名稱是“熱輔助記錄”（Thermal Assisted Recording，TAR）,。
　　(2) 納米磁島工藝,，增加磁顆粒尺寸
' ?' a% }1 p+ ~" @% N2 M　　為了提高存儲(chǔ)密度，慣常的思路是不斷縮小磁顆粒的尺寸,，這也是造成超順磁效應(yīng)的主要原因,。既然如此,，如果反其道而行之，豈不是很好,？你也許會(huì)問(wèn)：磁顆粒增大對(duì)存儲(chǔ)密度是否有影響呢,？答案是否定的。過(guò)去,，每個(gè)存儲(chǔ)單元都是由許許多多的小顆粒組成,，如果用一個(gè)大顆粒替代成千上萬(wàn)的小顆粒，既不會(huì)有熱攪動(dòng),，也不會(huì)有磁轉(zhuǎn)變?cè)胍�,，非常有利于提高磁記錄信息的穩(wěn)定性，也不會(huì)對(duì)存儲(chǔ)密度構(gòu)成影響,。工程師們把這個(gè)大顆粒稱作“單域磁島”(single domain magnetic island）,或者可以簡(jiǎn)稱“磁島”,，而將這種利用納米工藝制作的磁記錄層稱作晶格化磁介質(zhì)（patterned magnetic media）。

easylife

原帖由 紫木棉 于 2009-2-6 10:40 發(fā)表
7 Q$ Q% m9 a* {我在網(wǎng)上查閱了一下,，應(yīng)該就是你上面介紹的兩種方法吧,，不過(guò)只是粗略的介紹了一下。
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$ c7 j- s) @8 g9 \' p  O0 y1 N. v(1) 高溫讀寫,，常溫保持
　　從磁性材料的特性方面著手,，尋找更為穩(wěn)定的磁介質(zhì)（如鐵鉑粒子），可以在一定程度上解決超順磁效 ...

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# V+ S/ i3 k6 l7 d  G0 k印象中"熱輔助記錄技術(shù)"是希捷最先提出來(lái)的,，他們也應(yīng)該一直在做.

紫木棉

我覺(jué)得一直以來(lái),，機(jī)械硬盤中都是3.5"盤唱主角，其容量也是機(jī)械盤的指標(biāo),，目前西部數(shù)據(jù)已經(jīng)推出了2TB的3.5"盤,，而2.5"盤現(xiàn)在還是500G的水平。不過(guò)08年,，全球的筆記本銷售量已經(jīng)超過(guò)了臺(tái)式機(jī),，那將來(lái)2.5"盤是不是也會(huì)占據(jù)機(jī)械盤的主力位置？

easylife

3.5和2.5各有其特色,，
3 R' K* U+ f, y! A3.5注重其性能,，因?yàn)閼?yīng)用于非便攜產(chǎn)品，其重量和尺寸要求不那么嚴(yán)格,。
/ U" \+ d% V3 f3 o" z: R" E+ j為減短讀寫尋道時(shí)間,，VCM的Kt可取得很大，這樣磁頭運(yùn)動(dòng)更加靈活迅捷,，當(dāng)然,，會(huì)給VCM上鋼板安裝帶來(lái)困難，因?yàn)榇盆F間吸力最大可達(dá)到45Kg.
為減少主軸馬達(dá)高速運(yùn)動(dòng)下對(duì)磁頭性能的影響，硬盤越重越好,，而且重心要靠近主軸馬達(dá),，有時(shí)候?yàn)檫_(dá)到這個(gè)目的特意加上鐵塊...
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6 B. P0 j; h6 M! E而2.5注重其便攜性,，因此重點(diǎn)在盡可能減重,，并要考慮各種沖擊，跌落情況下的自我保護(hù),。
所以2.5硬盤盤體會(huì)很薄,，單碟產(chǎn)品重量100克左右徘徊。
可能會(huì)使用加速度傳感器檢測(cè)跌落撞擊來(lái)保護(hù)硬盤磁頭和碟片,。
內(nèi)部使用Rotary Latch保護(hù)磁頭臂組在非工作狀態(tài),，受到較大旋轉(zhuǎn)沖擊時(shí)不劃傷碟片。
設(shè)計(jì)時(shí)考慮非工作狀態(tài)下,，硬盤豎直跌落碟片震蕩可能碰到頂蓋和盤體,，這是不允許的 ....
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. s, J: s9 O' `" ?& m& y' I可見(jiàn)，從性能需要出發(fā),，我會(huì)選擇3.5,。如果出于娛樂(lè)的話，我更傾向于2.5,。
出于性能的考慮,，企業(yè)和需要做數(shù)據(jù)運(yùn)算之類的消費(fèi)者的主要需求還是在3.5，我想短期內(nèi)不會(huì)變的,。而大眾更傾向于便攜的筆記本,，2.5是必選品，經(jīng)濟(jì)危機(jī)過(guò)后,，上升趨勢(shì)應(yīng)該會(huì)很平穩(wěn)..
+ y$ k9 `9 a9 h( @+ m- m0 k以后2.5份額可能超過(guò)3.5...

紫木棉

溫度太高會(huì)損害硬盤,，那具體這個(gè)因?yàn)闇囟壬�高而引起的硬盤損害表現(xiàn)在那個(gè)方面？還有,，一般3.5"盤的殼溫要求在60攝氏度以下,，如果超過(guò)這個(gè)，將會(huì)導(dǎo)致MTBF（年平均故障率）大幅上升,，那當(dāng)殼溫達(dá)到60攝氏度時(shí),，馬達(dá)的溫度有多高，有沒(méi)有相關(guān)的數(shù)據(jù),？

easylife

原帖由 紫木棉 于 2009-2-18 23:34 發(fā)表
! }9 C/ V$ h- E, f, T2 U6 F% w  r溫度太高會(huì)損害硬盤,，那具體這個(gè)因?yàn)闇囟壬�高而引起的硬盤損害表現(xiàn)在那個(gè)方面？還有,，一般3.5"盤的殼溫要求在60攝氏度以下,，如果超過(guò)這個(gè)，將會(huì)導(dǎo)致MTBF（年平均故障率）大幅上升,，那當(dāng)殼溫達(dá)到60攝氏度時(shí),，馬達(dá)的溫 ...

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' z8 D2 j, c' Y+ w  \根據(jù)個(gè)人理解,，
7 U( c3 s4 P; _& ?6 i硬盤內(nèi)部有精密注塑的塑料件--Ramp等, 還有起密封作用的橡膠件，以及多種高分子材料合成的軟線路板,，聯(lián)接用的各種膠水,，軸承內(nèi)部的潤(rùn)滑油。,。,。
溫度過(guò)高，會(huì)使得各種化學(xué)物質(zhì)蒸發(fā)（,？）到空氣中,，造成部件的腐蝕。
溫度過(guò)高,，會(huì)使得精密注塑的注塑件尺寸發(fā)生變化,，嚴(yán)重時(shí)可能影響到磁頭的歸位（unload)和正常的滑行到碟片(load)�,？赡軗p壞磁頭懸臂結(jié)構(gòu)或者滑傷磁頭和碟片,。
溫度過(guò)高，會(huì)使得碟片發(fā)生膨脹,，其徑向的膨脹將使得各磁軌相對(duì)距離發(fā)生變化,，若碟片軌密度(TPI-Track per inch)較高，可能造成伺服控制困難--無(wú)法找到正確的軌道,。
溫度過(guò)高,，若此密度很大，其能量也可能能改變磁單元磁極--純屬臆測(cè),，想法來(lái)源于超磁導(dǎo)效應(yīng)..
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殼溫達(dá)到60攝氏度時(shí),，馬達(dá)的溫度？沒(méi)有研究過(guò),，不過(guò)猜想應(yīng)該比鋁或不銹鋼的上蓋殼體和鋁的盤體高,，因?yàn)橛脖P熱量大部分產(chǎn)生于主軸馬達(dá)的旋轉(zhuǎn)運(yùn)行。

easylife

忘記說(shuō)了,，
溫度過(guò)高,  電路板上芯片也可能工作不正常,，